Method of treating oils



Aug. 8, 1939. H. D. No| y 2,168,875

METHOD of' HEATING oILs Filed July 8, 1937 Ca s OMR, WATER f/VLETJ. 35FINVENTOR Patented Aug. s, 1939v UNITED STATES PATENT OFFICE cony-VaeuumOil Company,

Incorporated,

New York, N. Y., a. corporation of New York Application July 8, 1937,Serial No. 152,513

1 Claim.

This invention has to do with solvent refining of petroleum lubricantoil fractions to produce therefrom products of higher parafllnicity.Solvent refining is accomplished by mixing with the oil to be treated asolvent refining agent capable of exerting selective solvent power forone of the classes of constituents therein, allowing phase separation,and withdrawing the solvent and the extracted constituents dissolvedtherein. Either the extract or the non-dissolved portion may be thedesired product depending upon the solvent.

Two solvents. one preferential for naphthenic constituents, and onepreferential for paraflinic constituents, may be used simultaneously, ina similar manner. A modification of the double solvent process is onewherein a solvent preferentially dissolving oils of a 'parafilnic natureis passed through a series of treating stages, each composed of a mixingstep and a settling step; a solvent preferentially dissolving naphthenicoils is passed through the same series in the opposite direction, andoil to be treated is introduced to some intermediate stage in theseries. It is with such a system oi double solvent refining that thisinvention is specifically concerned.

In the usual commercial practice of this double solvent refiningprocess, the parafflnic solvent used is a mixture of liquefied normallygaseous hydrocarbons consisting predominantly of propane with minorproportions of related compounds. This reagent is hereinafter referredto as propane. The usual naphthenic solvent isl a mixture of phenolicmaterials of the nature of tar acids, consisting mostly of cresylicacids, with smaller amounts of related phenols, hereinafter referred toas selecto.

The present commercial practice oi double solvent refining, the relationof this invention thereto, and the present invention may be understoodmost readily by reference to the drawing attached to this specification.In the drawing, Figure 1 indicates the present practice, and Figure 2indicates practice according to my invention, both by diagrammatic owsheets.

Referring now to Figure 1 of the drawing, showing present practice, thesystem consists of a container 3, housing a series of chambers 4, 5, 6,1, 8, 9 separated by imperforate partitions I0, II, I2, I3, I4. A fewmore, or one or two less chambers may appear in any individualcommercial setup, dependent upon its particular duty. Each of thesechambers constitutes a settling zone wherein a mixture of oil, parafnicsolvent, and naphthenic solvent may separate into an upper layer ofrafnate composed of paraiiinic oil and paramnic solvent and `a lowerlayer of extract composed of naphthenic oils and naphthenic solvent, asshown by the arrows and liquid lining therein. Partitions Ii), I2, I3,I4

are equipped with a mixing jet as shown, de`

noted in each case by the numeral I5, which withdraws raiiinate layerfrom the preceding compartment over a Weir designated in each case bynumeral- I6. Partition II and the end plate of chamber 4 are fitted withentry nozzles denoted by I1 for diffusion of outside formed mixtures.Naphthenic solvent is introduced by pipe I8 through jet mixer I5intochamber 9, entraining and carrying with it raffinate from chamber 8.Settled, extract from chamber 9 passes through pipe I9, pump 20, andpipe 2| through a jet mixer into chamber 8, admixed with rainate fromchamber 1. Extract from cham ber 8 similarly passes through 22, 23, 24into chamber 1. Extract from chamber 1 passes through pipe 25 and pump26 into mixer 21. Oil chargedv to the system for refining enters throughpipe 28 and pump 29 to mixer 21. Railinate from chamber passes throughpipe 30, pump 3| and pipe 32 to mixer 21, The mixture from 21 is passedthrough cooler 33 and pipe 34 into chamber 6. Extract from chamber 6passes through pipe 35l pump 36, pipe 31 into chamber 5. Extract fromchamber 5 passes through pipe 38, pump 39, pipe 40, and pipe 4I intochamber 4. Extract from chamber 4 is withdrawn by pipe 42, constitutingthe extract product of the system, and is an equilibrium mixture ofnaphthenic oils, naphthenic solvent, and some paraiiinic solvent.Paralnic solvent enters the system through pipe 4I, passes to therafnate phase in chamber 4, thence to chamber 5 by 30, 3|, 32, 21, 33,34, to chamber 6, to 1, 8, and 9, and raffinate withdrawn by pipe 43from chamber. 9 constitutes the ralnate product of the system and is anequilibrium mixture of paralnic oils, paraiinic solvent, and somenaphthenic solvent.

In the usual case the parailinic solvent and naphthenic solvent, propaneand selecto respectively, are each applied in the amount of about fourtimes the weight of the oil introduced. In such a system, with one partof oil per time unit at a temperature of about 180-190 F., about fourparts of propane at a temperature of about 85- 95 F., and somewhat lessthan four parts of selecto at about 'T0-'75 F. the temperature inchamber 6 adjusted by the cooler 33 for best operation of chamber 6 andsubsequent chambers 1 9, will be about 75-90" F. The temperature ."nchambers 5 and 6, as determined by the temperature in chamber 6 and thetemperature of entering propane, will be about 77-90" F. in chamber 5and 85-95 F. in chamber 4.

The system combines two functions. 'I'he first is that of separatingnaphthenic oils from parafnic oils, carried out in 6, 1, and subsequentchambers. The other is that of separating paraiiinic oils from extract,carried out in chambers 5 and 4. The deasphaltizing action of chambers 5and 4 becomes more sharp and emof a system cient with increasingtemperature. That is, for the same proportions of extract and propane,or oil and propane in the presence of selecto. a greater freedom ofparaillnic fractions from extract will be attained with increasingtemperature. The best temperature level is usually above 100 F. in therange 10D-120 F. In the upper end of the system, in chambers 6, 1, t,etc., the function of separation of naphthenic oils from paratflnic oilsis made more eiiiclent by lower temperatures, of the order of rI590 F.and lower. If higher, too much propane is soluble in the extract layer,carrying with it valuable parafflnic oils. Since these two functions, ofunlike temperature requirements, are practiced as connected portions ofa unitary system, the control is for the more important function, thattaking place in chambers 5, 1, 8, etc. This results in an undue loss ofparalnic material in extract from chamber 4, and as well in a decreaseof capacity for the system as a whole. This invention has for its objectthe provision which, while preserving those undoubted advantages arisingfrom flowing a parafflnic solvent and a naphthenic solventcountercurrent through a series of stages each comprising a mixing and asettling step, and introducing oil at 'a` point intermediate the endsthereof, also permits the separation of the two functional parts thereofand their independent control in a manner best suited to the needs ofeach.

The invention may be understood by reference to Figure 2 of the drawing,and its comparison with Figure 1. In Figure 2, 44 is a container housingchambers 45 and 46, and 41 is another container housing chambers 48, 49,50, 5I. As before, the number of chambers may vary slightly in responseto the necessities of commercial design. The extract precipitation andstripping function is housed in 44 and the recovery of paraffinic fromnaphthenic oils is housed in 41. The separation is for the purpose ofisolating 44 in a temperature sense from 41, and may be carried outequally well by joining 44 and 41 physically, as shown by dotted lines,but thoroughly insulating chamber 48 from chamber 46, as likewise shownin dotted lines. The internal functioning and the general arrangement ofthe chambers is the same as in Figure 1. Paraiinic solvent entersthrough pipe 52, passes into the raffinate phase, through chambers 45,46, pipe 53, pump 54, pipe 55, mixer 56, cooler 51, pipe 58, chambers48, 49, 50, 5|, and out with raffinate through pipe 59. Naphthenicsolvent enters as before through pipe 60. Extract from 5I is transferredto 50 by pump 6l. Extract from 58 is transferred by pump 62 to 49.Extract from 49 is transferred by pump 63 to mixer 56. However, oilcharge is not introduced to this mixer, and the chambers 48-51 inclusiveare charged only with the duty of most efficiently separating a mixtureof naphthenic and paraffinic oils, comparatively rich in paraffinicconstituents, and the temperature therein, effected by use of cooler 51,is that best adapted for such operation. Oil charge introduced to thesystem by pump 64 passes through pipe 65 into chamber 46, in admixturewith raffinate from chamber 45. There, at a comparatively hightemperature level, in the presence of a relatively high proportion ofpropane and low proportion of selecto, it is effectively deasphaltized,to yield a comparatively parafiine-rich and comparatively asphalt-freemixture of parafllnic and naphthenic oils to pass as raffinate throughpipe 53, pump 54, pipe 55, mixer 56 and cooler 51 into the upper portionof the system. Extract from chamber 48 passes through pipe 66, pump 61and pipe 68 into pipe 52. Extract from chamber 46 passes through pipe69, pump 10, and pipe 1i into pipe 52. These extracts admixed in pipe 52with paratfinic solvent pass into chamber 45. In that chamber, due tothe presence of propane, entirely free from paraflinic constituents ofthe oil, at a properly high temperature level, a. maximum separationfrom the extract of the paraffinic constituents entrained therein can beattained.

Thus it will be seen that without any sacriflce of the usefulcharacteristics of the general system, my invention has enabled me to soseparate the several functions thereof so as to best serve the demandsof each and to secure the most efficient operation of each function. Mysystem of operation, without substantial change in proportion ofsolvents applied will thus permit of an increase in the yield ofparaflinic constituents. a greater parafiinicity of the raffinate, and alower Conradson carbon content of the recovered refined oil. For asystem housed in an apparatus of a given size, equipped with a givencooling capacity, the adoption of the method of operation disclosedherein, including the indicated heat insulation, will result in amaterial increase in daily through-put capacity.

As indicated, when operating according to this system, charging one partby weight of oil per unit time at a temperature of 180-190 F., and aboutfour parts of selecto at about 'I0-'15 F., the temperature in chamber 48would be about 15-90 F., while that in chambers 45 and 4B would be ofthe order of 10U-120 F., and would be effected by feeding propane at ahigher temperature than before, say at about F. i

It will be understood that the numerical data given herein is set forthonly by way of example, and' that the invention is not limited therebyor thereto, but is subject only to those limits expressly set forth inthe following claim.

In the solvent treatment of petroleum lubricant fractions bycounterflowing parafiinic and naphthenic solvents through a plurality ofextractive stages and introducing oil to an inter- .mediate stage of theseries, the improvement which comprises maintaining the oil introductionstage and all stages prior thereto in the direction of paraffinicsolvent flow at a temperature level substantially higher than thatobtaining in the stage next subsequent and in any other following stagein the direction of paraffinic solvent flow, while maintaining the samerate of paraflinic solvent flow throughout all stages of the series, andby-passing naphthenic solvent and extract from the first stagesubsequent to oil introduction to the first stage prior to oilintroduction, whereby enhanced separation of oil into parailinic andnon-parafiinic oil constituents may be obtained for a given ratio ofsolvents.

HENRY D. NOLL.

